1. Field of Art
The present invention relates to a combination sintering-annealing furnace, and particularly to such a combination furnace wherein the waste heat from the furnace for sintering ceramic shell molds is utilized to establish a desired heat distribution in an adjacent annealing furnace for slowly cooling the cast material contained in the ceramic shell molds.
A cast product prepared, for example, through the lost-wax casting process frequently suffers cracking or other failures particularly at a thin wall portion thereof. Such crackings or fine fissures are caused by the stress in the cast material during the course of cooling, the stress resulting from the difference in shrinkage between the cast material and the mold.
2. Prior Art
It has been proposed to control the cooling rate of the cast material in order to prevent an occurrence of cracking at the thin wall portion of the cast product. In the conventional cooling furnaces used for this purpose, an individual heat source separated from the heat source for the sintering furnace is used or the waste gas from the sintering furnace is passed to the cooling furnace installed away from the sintering furnace at a long distance. A vast investment is required for the blower means and the heat-insulated piping equipment in the conventional plant for combining the sintering furnace with the cooling furnace, in addition to a complicated design task requested for the establishment of optimum heat distribution in the cooling furnace.